Mercurial > hg > graal-compiler
view src/share/vm/services/lowMemoryDetector.cpp @ 2149:7e37af9d69ef
7011379: G1: overly long concurrent marking cycles
Summary: This changeset introduces filtering of SATB buffers at the point when they are about to be enqueued. If this filtering clears enough entries on each buffer, the buffer can then be re-used and not enqueued. This cuts down the number of SATB buffers that need to be processed by the concurrent marking threads.
Reviewed-by: johnc, ysr
author | tonyp |
---|---|
date | Wed, 19 Jan 2011 09:35:17 -0500 |
parents | f95d63e2154a |
children | 3582bf76420e |
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/* * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #include "precompiled.hpp" #include "classfile/systemDictionary.hpp" #include "classfile/vmSymbols.hpp" #include "oops/oop.inline.hpp" #include "runtime/interfaceSupport.hpp" #include "runtime/java.hpp" #include "runtime/javaCalls.hpp" #include "runtime/mutex.hpp" #include "runtime/mutexLocker.hpp" #include "services/lowMemoryDetector.hpp" #include "services/management.hpp" LowMemoryDetectorThread* LowMemoryDetector::_detector_thread = NULL; volatile bool LowMemoryDetector::_enabled_for_collected_pools = false; volatile jint LowMemoryDetector::_disabled_count = 0; void LowMemoryDetector::initialize() { EXCEPTION_MARK; instanceKlassHandle klass (THREAD, SystemDictionary::Thread_klass()); instanceHandle thread_oop = klass->allocate_instance_handle(CHECK); const char thread_name[] = "Low Memory Detector"; Handle string = java_lang_String::create_from_str(thread_name, CHECK); // Initialize thread_oop to put it into the system threadGroup Handle thread_group (THREAD, Universe::system_thread_group()); JavaValue result(T_VOID); JavaCalls::call_special(&result, thread_oop, klass, vmSymbolHandles::object_initializer_name(), vmSymbolHandles::threadgroup_string_void_signature(), thread_group, string, CHECK); { MutexLocker mu(Threads_lock); _detector_thread = new LowMemoryDetectorThread(&low_memory_detector_thread_entry); // At this point it may be possible that no osthread was created for the // JavaThread due to lack of memory. We would have to throw an exception // in that case. However, since this must work and we do not allow // exceptions anyway, check and abort if this fails. if (_detector_thread == NULL || _detector_thread->osthread() == NULL) { vm_exit_during_initialization("java.lang.OutOfMemoryError", "unable to create new native thread"); } java_lang_Thread::set_thread(thread_oop(), _detector_thread); java_lang_Thread::set_priority(thread_oop(), NearMaxPriority); java_lang_Thread::set_daemon(thread_oop()); _detector_thread->set_threadObj(thread_oop()); Threads::add(_detector_thread); Thread::start(_detector_thread); } } bool LowMemoryDetector::has_pending_requests() { assert(LowMemory_lock->owned_by_self(), "Must own LowMemory_lock"); bool has_requests = false; int num_memory_pools = MemoryService::num_memory_pools(); for (int i = 0; i < num_memory_pools; i++) { MemoryPool* pool = MemoryService::get_memory_pool(i); SensorInfo* sensor = pool->usage_sensor(); if (sensor != NULL) { has_requests = has_requests || sensor->has_pending_requests(); } SensorInfo* gc_sensor = pool->gc_usage_sensor(); if (gc_sensor != NULL) { has_requests = has_requests || gc_sensor->has_pending_requests(); } } return has_requests; } void LowMemoryDetector::low_memory_detector_thread_entry(JavaThread* jt, TRAPS) { while (true) { bool sensors_changed = false; { // _no_safepoint_check_flag is used here as LowMemory_lock is a // special lock and the VMThread may acquire this lock at safepoint. // Need state transition ThreadBlockInVM so that this thread // will be handled by safepoint correctly when this thread is // notified at a safepoint. // This ThreadBlockInVM object is not also considered to be // suspend-equivalent because LowMemoryDetector threads are // not visible to external suspension. ThreadBlockInVM tbivm(jt); MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); while (!(sensors_changed = has_pending_requests())) { // wait until one of the sensors has pending requests LowMemory_lock->wait(Mutex::_no_safepoint_check_flag); } } { ResourceMark rm(THREAD); HandleMark hm(THREAD); // No need to hold LowMemory_lock to call out to Java int num_memory_pools = MemoryService::num_memory_pools(); for (int i = 0; i < num_memory_pools; i++) { MemoryPool* pool = MemoryService::get_memory_pool(i); SensorInfo* sensor = pool->usage_sensor(); SensorInfo* gc_sensor = pool->gc_usage_sensor(); if (sensor != NULL && sensor->has_pending_requests()) { sensor->process_pending_requests(CHECK); } if (gc_sensor != NULL && gc_sensor->has_pending_requests()) { gc_sensor->process_pending_requests(CHECK); } } } } } // This method could be called from any Java threads // and also VMThread. void LowMemoryDetector::detect_low_memory() { MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); bool has_pending_requests = false; int num_memory_pools = MemoryService::num_memory_pools(); for (int i = 0; i < num_memory_pools; i++) { MemoryPool* pool = MemoryService::get_memory_pool(i); SensorInfo* sensor = pool->usage_sensor(); if (sensor != NULL && pool->usage_threshold()->is_high_threshold_supported() && pool->usage_threshold()->high_threshold() != 0) { MemoryUsage usage = pool->get_memory_usage(); sensor->set_gauge_sensor_level(usage, pool->usage_threshold()); has_pending_requests = has_pending_requests || sensor->has_pending_requests(); } } if (has_pending_requests) { LowMemory_lock->notify_all(); } } // This method could be called from any Java threads // and also VMThread. void LowMemoryDetector::detect_low_memory(MemoryPool* pool) { SensorInfo* sensor = pool->usage_sensor(); if (sensor == NULL || !pool->usage_threshold()->is_high_threshold_supported() || pool->usage_threshold()->high_threshold() == 0) { return; } { MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); MemoryUsage usage = pool->get_memory_usage(); sensor->set_gauge_sensor_level(usage, pool->usage_threshold()); if (sensor->has_pending_requests()) { // notify sensor state update LowMemory_lock->notify_all(); } } } // Only called by VMThread at GC time void LowMemoryDetector::detect_after_gc_memory(MemoryPool* pool) { SensorInfo* sensor = pool->gc_usage_sensor(); if (sensor == NULL || !pool->gc_usage_threshold()->is_high_threshold_supported() || pool->gc_usage_threshold()->high_threshold() == 0) { return; } { MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); MemoryUsage usage = pool->get_last_collection_usage(); sensor->set_counter_sensor_level(usage, pool->gc_usage_threshold()); if (sensor->has_pending_requests()) { // notify sensor state update LowMemory_lock->notify_all(); } } } // recompute enabled flag void LowMemoryDetector::recompute_enabled_for_collected_pools() { bool enabled = false; int num_memory_pools = MemoryService::num_memory_pools(); for (int i=0; i<num_memory_pools; i++) { MemoryPool* pool = MemoryService::get_memory_pool(i); if (pool->is_collected_pool() && is_enabled(pool)) { enabled = true; break; } } _enabled_for_collected_pools = enabled; } SensorInfo::SensorInfo() { _sensor_obj = NULL; _sensor_on = false; _sensor_count = 0; _pending_trigger_count = 0; _pending_clear_count = 0; } // When this method is used, the memory usage is monitored // as a gauge attribute. Sensor notifications (trigger or // clear) is only emitted at the first time it crosses // a threshold. // // High and low thresholds are designed to provide a // hysteresis mechanism to avoid repeated triggering // of notifications when the attribute value makes small oscillations // around the high or low threshold value. // // The sensor will be triggered if: // (1) the usage is crossing above the high threshold and // the sensor is currently off and no pending // trigger requests; or // (2) the usage is crossing above the high threshold and // the sensor will be off (i.e. sensor is currently on // and has pending clear requests). // // Subsequent crossings of the high threshold value do not cause // any triggers unless the usage becomes less than the low threshold. // // The sensor will be cleared if: // (1) the usage is crossing below the low threshold and // the sensor is currently on and no pending // clear requests; or // (2) the usage is crossing below the low threshold and // the sensor will be on (i.e. sensor is currently off // and has pending trigger requests). // // Subsequent crossings of the low threshold value do not cause // any clears unless the usage becomes greater than or equal // to the high threshold. // // If the current level is between high and low threhsold, no change. // void SensorInfo::set_gauge_sensor_level(MemoryUsage usage, ThresholdSupport* high_low_threshold) { assert(high_low_threshold->is_high_threshold_supported(), "just checking"); bool is_over_high = high_low_threshold->is_high_threshold_crossed(usage); bool is_below_low = high_low_threshold->is_low_threshold_crossed(usage); assert(!(is_over_high && is_below_low), "Can't be both true"); if (is_over_high && ((!_sensor_on && _pending_trigger_count == 0) || _pending_clear_count > 0)) { // low memory detected and need to increment the trigger pending count // if the sensor is off or will be off due to _pending_clear_ > 0 // Request to trigger the sensor _pending_trigger_count++; _usage = usage; if (_pending_clear_count > 0) { // non-zero pending clear requests indicates that there are // pending requests to clear this sensor. // This trigger request needs to clear this clear count // since the resulting sensor flag should be on. _pending_clear_count = 0; } } else if (is_below_low && ((_sensor_on && _pending_clear_count == 0) || (_pending_trigger_count > 0 && _pending_clear_count == 0))) { // memory usage returns below the threshold // Request to clear the sensor if the sensor is on or will be on due to // _pending_trigger_count > 0 and also no clear request _pending_clear_count++; } } // When this method is used, the memory usage is monitored as a // simple counter attribute. The sensor will be triggered // whenever the usage is crossing the threshold to keep track // of the number of times the VM detects such a condition occurs. // // High and low thresholds are designed to provide a // hysteresis mechanism to avoid repeated triggering // of notifications when the attribute value makes small oscillations // around the high or low threshold value. // // The sensor will be triggered if: // - the usage is crossing above the high threshold regardless // of the current sensor state. // // The sensor will be cleared if: // (1) the usage is crossing below the low threshold and // the sensor is currently on; or // (2) the usage is crossing below the low threshold and // the sensor will be on (i.e. sensor is currently off // and has pending trigger requests). void SensorInfo::set_counter_sensor_level(MemoryUsage usage, ThresholdSupport* counter_threshold) { assert(counter_threshold->is_high_threshold_supported(), "just checking"); bool is_over_high = counter_threshold->is_high_threshold_crossed(usage); bool is_below_low = counter_threshold->is_low_threshold_crossed(usage); assert(!(is_over_high && is_below_low), "Can't be both true"); if (is_over_high) { _pending_trigger_count++; _usage = usage; _pending_clear_count = 0; } else if (is_below_low && (_sensor_on || _pending_trigger_count > 0)) { _pending_clear_count++; } } void SensorInfo::oops_do(OopClosure* f) { f->do_oop((oop*) &_sensor_obj); } void SensorInfo::process_pending_requests(TRAPS) { if (!has_pending_requests()) { return; } int pending_count = pending_trigger_count(); if (pending_clear_count() > 0) { clear(pending_count, CHECK); } else { trigger(pending_count, CHECK); } } void SensorInfo::trigger(int count, TRAPS) { assert(count <= _pending_trigger_count, "just checking"); if (_sensor_obj != NULL) { klassOop k = Management::sun_management_Sensor_klass(CHECK); instanceKlassHandle sensorKlass (THREAD, k); Handle sensor_h(THREAD, _sensor_obj); Handle usage_h = MemoryService::create_MemoryUsage_obj(_usage, CHECK); JavaValue result(T_VOID); JavaCallArguments args(sensor_h); args.push_int((int) count); args.push_oop(usage_h); JavaCalls::call_virtual(&result, sensorKlass, vmSymbolHandles::trigger_name(), vmSymbolHandles::trigger_method_signature(), &args, CHECK); } { // Holds LowMemory_lock and update the sensor state MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); _sensor_on = true; _sensor_count += count; _pending_trigger_count = _pending_trigger_count - count; } } void SensorInfo::clear(int count, TRAPS) { if (_sensor_obj != NULL) { klassOop k = Management::sun_management_Sensor_klass(CHECK); instanceKlassHandle sensorKlass (THREAD, k); Handle sensor(THREAD, _sensor_obj); JavaValue result(T_VOID); JavaCallArguments args(sensor); args.push_int((int) count); JavaCalls::call_virtual(&result, sensorKlass, vmSymbolHandles::clear_name(), vmSymbolHandles::int_void_signature(), &args, CHECK); } { // Holds LowMemory_lock and update the sensor state MutexLockerEx ml(LowMemory_lock, Mutex::_no_safepoint_check_flag); _sensor_on = false; _pending_clear_count = 0; _pending_trigger_count = _pending_trigger_count - count; } } //-------------------------------------------------------------- // Non-product code #ifndef PRODUCT void SensorInfo::print() { tty->print_cr("%s count = %ld pending_triggers = %ld pending_clears = %ld", (_sensor_on ? "on" : "off"), _sensor_count, _pending_trigger_count, _pending_clear_count); } #endif // PRODUCT